Mr. Hart was selected as an astronaut candidate by NASA in January 1978. In August 1979, he completed a 1-year training and evaluation period, making him eligible for flight assignment on future Space Shuttle crews. Hart was also member of the support crews for STS-1, STS-2, STS-3, and STS-7. He was Ascent and Orbit CAPCOM with the Mission Control Team for those flights. He flew as a mission specialist on STS-41-C (April 6-April 13, 1984) and has logged a total of 168 hours in space.

From 1968 to 1978, Hart was employed as a member of the Technical Staff of Bell Telephone Laboratories. His principal duties included electrical and mechanical design responsibilities for a variety of electronic power equipment used in the Bell System. He has received 2 patents.

After leaving NASA, he was the Director of Engineering and Operations for AT&T's satellite network. He is currently a member of the Engineering faculty at Lehigh University.